Various means have been used to attach heat sinks in intimate thermal contact with electronic device packages. For purposes of this disclosure, a heat sink is any body of metal or like material which is placed in contact with an electronic device package for transferring heat from the device contained in the device package and rapidly dissipating the heat to the atmosphere by conduction convection and/or radiation. For instance, it is known to glue or otherwise adhesively attach a heat sink to an electronic device package. However, assembly of the heat sink to the electronic device package is messy, tedious, labor intensive, requires accurate alignment of the parts. It is therefore expensive. Many commonly used adhesives emit fumes or otherwise constitute an undesirable health hazard. Frequently, it is necessary to cure the adhesive at elevated temperatures for extended periods of time, further increasing manufacturing costs. It is also sometimes desirable to remove the heat sink from the electronic device package for repair or replacement. This is extremely difficult, if not impossible, to accomplish when the heat sink is adhesively mounted on the electronic device package.
Heat sinks are also mechanically attached to electronic device packages such as by resilient metal clips mounted on the heat sinks which urge the heat sinks and the electronic device packages into mutual contact. The clip enables the heat sink to be easily removed from the electronic device package. However, this approach is undesirable in several respects. For instance, the clip relies solely on frictional engagement between the clip and the electronic device package to secure the heat sink thereto. Vibration, gravity or other mechanical forces may tend to loosen the heat sink from the electronic device package. Furthermore, since the heat sink is not positively locked into position on the electronic device package, there is a tendency for the clip to inadvertently contact the leads extending from the electronic device package and thereby create an electrical short between the leads. Generally, such clips are constructed so as to extend substantially the full length of the electronic device package. Therefore, the force urging the heat sink and the electronic device package together is applied at an end of the electronic device package rather than at an intermediate point where heat is being generated. This renders the heat sink less effective in dissipating heat from the electronic device package.